Date: Fri, 11 Apr 2003 17:21:16 +0200 (CEST) From: Emmanuel Tsesmelis Subject: TSTB NEWS 030411 - Additional Information for SPS LHC-type Beams Dear Colleagues, As for the equivalent 2001 SPS run with the LHC-type beams, the precise frequency at 400 GeV/c is 40.078856 MHz, resulting in a bunch spacing of 24.95 ns. The stability of the frequency is much better than 100 ppm. Best regards, Emmanuel ============================================================================ From Emmanuel.Tsesmelis@cern.ch Tue Apr 8 17:33:56 2003 Date: Tue, 8 Apr 2003 17:26:05 +0200 (CEST) From: Emmanuel Tsesmelis Subject: TSTB NEWS 030408 - Beam Parameters for 25 ns SPS Run Dear Colleagues, In Period P1A of the 2003 SPS proton run, LHC-type beams with a 25 ns bunch spacing will available in the West and North Area secondary beamlines. The conditions will be similar to those available during the previous such run in 2001 and are given below: o 400 GeV beam energy o 16.8 s cycle length o 2.7 s Slow Extraction duration o 48 bunches with 25 ns spacing between bunches --> 48 * 25 ns = 1200 ns bunch train length with 1 bunch train per 23 microsecs o The bunch length was measured in 2001 to be 2.3 ns at the base. Due to radiation safety limits, there are restrictions on the maximum number of particles that can be sent to the experimental areas. With the limit of 10^6 protons per spill in the West Area zones, the average number of protons would be 0.18 p/bunch for a 2.7 s Slow Extraction. This limit is a few times 10^6 protons per spill in the North Area with the corresponding increase in the number of protons per spill. Collimation may be used to tune the intensity in the secondary zones. Earlier measurements at the SPS for the conditions at the West Area show that the bunch population with the 2.7 s flat-top are similar to those expected at the LHC. Timing signals from the accelerator will be available in the counting rooms of the experiments. Both the 40 MHz machine clock from the RF Faraday Cage and the 43 kHz SPS orbit signal will be distributed as in the past via the TTC system using optical fibre transmitters and receivers developed by RD12. Best regards, Emmanuel Tsesmelis